Relatives say shots rang out after Estrada saw two people in ski masks and hoodies trying to rob his daughter and her boyfriend at gunpoint in the parking lot as they carried food from a car. Police say as the 50-year-old reached for his gun to stop the robbers, he was shot in the chest.

A procession of law enforcement vehicles accompanied the body of the officer from Loyola Medical Center, where he was pronounced dead by the Cook County Medical Examiner's office.

"It touched our heart because it's so close to the holidays and Christmastime, and so we really are taking this seriously and we want to catch the offenders as soon as possible," said Andre Harvey, director of public safety, Bellwood.

Before joining the Cook County Sheriff's police, Estrada was a Marine who served in Desert Storm. He was a father of four and grandfather to three. Friends say he was active in the organizing community activities.

"We worked together throughout the community and we argued about things here in the community a lot, and we both tried to do our part," said Lennel Grace, victim's friend.

Standing outside a relative's home Saturday afternoon, all Christina Estrada could do is cry, while she grasped the pendant necklace her father gave his daughters. It's in the shape of a miniature gold Cook County Sheriff's badge with his star number on it.

"He was just a good person, a father, he was always there for us. He just wanted us to succeed in life," said Christina Estrada.

Police search for offenders who killed off-duty officer

Investigators were at the scene Saturday, piecing together the moments that led to the deadly shooting.

The streets around the VFW Hall where he was shot remained closed for several hours while the Bellwood police and other authorities combed the scene for evidence. The West Suburban Crimes Task Force and the Cook County Sheriff's Office have joined in the investigation.

Cook County Sheriff Tom Dart was on the scene along with investigators.

"The deputy worked with us over 20 years, an amazing family man, who is going to be missed by be everybody. I worked with him myself, and he was an amazing person -- funny, caring, thoughtful, and this is tragic," Dart said. "Everyone is just stunned."

Investigators have not said how many people they believe might have been involved between the armed robbery and the shooting, and so far, no one is in custody.